1. Field of the Invention
The present invention relates to an insulator pressure-cut connector terminal for connecting a core conductor of a wire to a connector terminal by pressure-fitting the wire into at least one insulator cutting open slot formed in a cutter plate of the connector terminal, without stripping the insulating cover material from the wire, and in particular to an insulator pressure-cut connector terminal suitable for use in connecting a large- or small-diameter wire thereto.
2. Description of the Prior Art
Recently, wire insulator pressure-cut connector terminals (referred to as pressure-cut terminals, hereinafter) have been widely used to improve the productivity in the assembly process of automotive vehicles, for instance, because insulator covered wires (referred to wires, hereinafter) can be connected to the pressure-cut terminal by simply pushing the wire to at least one slot for cutting the wire insulator in such a condition that the core conductor of the wire is securely brought into contact with the slot formed in a cutter plate of the pressure-cut terminal.
FIG. 1 shows an example of the prior-art pressure-cut terminals, which roughly comprises a base plate 1, a female connector portion 2, and an insulator pressure-cutting porting 3. In more detail, a male terminal tab (not shown) can be inserted into a space formed between the female connector portion 2 and an inwardly bent spring portion 8. The insulator pressure-cutting portion 3 is formed into a box shape having two opposing wire cutter plates 4 and 5 formed with an insulator pressure-cutting open slot 6 or 7, respectively. In this pressure-cut terminal, when the insulated wire is fitted into these pressure-cutting open slots 6 and 7, the insulating cover thereof is cut off and therefore the core conductor is brought into direct contact with the insulator pressure-cutting portion 3, so that it is possible to improve the productivity of the connecting work of the wire to the connector terminal.
In the above-mentioned prior-art pressure-cut terminal, however, there exists a following problem: when a relatively large diameter wire is pressure fit into these cutting open slots 6 and 7, the two opposing cutter plates 4 and 5 are easily deformed and therefore the wire conductor contact reliability is not high. To overcome the above-mentioned problem, when the thickness of the pressure-cut plates 4 and 5 is increased, there causes another problem in that the elastic force of the spring portion 8 is excessively increased so that it is rather difficult to engage the male terminal tab (not shown) with the female connector portion 2.
To overcome the above-mentioned problem, the same applicant has already proposed a pressure-cut terminal in which the insulator pressure-cutting portion is formed by a relatively thick plate and the female connector portion is formed by a relatively thin plate integral with the insulator pressure-cutting portion 3, as disclosed in U.S. Pat. No. 4,593,963. In this prior-art terminal, however, since a plate material having two different thicknesses must be prepared, there exists another problem in that the material cost inevitably increases.
To overcome the above-mentioned problem, another pressure-cut terminal 10 as shown in FIGS. 2(A) and (B) has been proposed, which comprises: a flat box-shaped female terminal end 11, a U-shaped section wire connecting portion 12, and a separate cutter plate 14 formed with a downward extending cutting open slot 14a. In this terminal, a wire 13 is inserted into the wire connecting portion 12 and then the cutter plate 14 is pushed from above into the U-shaped section wire connecting portion 12 so that the cutter plate 14 can be fixed to the wire connecting portion 12. In this prior-art pressure-cut terminal, since two lower knife portions 15 of the cutter plate 14 cut the insulating cover material 16 of the wire 13, the core conductor 17 of the wire 13 can be electrically connected to the cutter plate 14.
In this case, since the thickness of the cutter plate 14 can be determined freely according to the diameter of the wire, it is possible to prevent the cutter plate 14 from being deformed by appropriately determining the thickness of the cutter plate 14 and the width of the cutting open slot 14a according to the diameter of the wire 13. Therefore, when a plurality of cutter plates 14 of different thickness are prepared according to the diameters of the wires 13, it is possible to reliably cut and connect the wire 13 to the cutter plate 14. Further, since the plate thickness of the terminal end 11 can be determined independently from the cutter plate 14, it is possible to easily engage a mated male terminal tab (not shown) with the female terminal end 11. In the above-mentioned prior-art pressure-cut terminal, however, since the core conductor 17 of the wire 13 is indirectly connected to the wire connecting portion 12 via the cutter plate 14, there still exists a problem in that the electrical contact stability is not sufficient and stable, because the cutter plate 14 is in contact with the wire connecting portion 12 through only partial side surfaces of the cutter plate 14 or the wire conductor 17 of the wire 13 is indirectly connected to the wire connecting portion 12 via the cutter plate 14 in the pressure-cut terminal 10.